The present invention relates to an ink-jet head, an ink-jet head with a bubble extracting device for eliminating bubbles in the ink-jet head, and an ink-jet type printing apparatus using the ink-jet head.
Conventionally, an ink-jet head which includes an ink storing chamber, at least one orifice having one end communicating with the ink storing chamber and the other end opened in an external space, and an ink ejection driving element provided in the orifice to eject ink in the orifice from the opening at the other end, has been well known.
An ink-jet type printing apparatus using the ink-jet head has such advantages that a constitution for color printing is simple, noise generated in the operation is small, and printing speed is high.
Each of Jpn. Pat. Appln. KOKOKU Publication No. 2-51734 and Jpn. Pat. Appln. KOKAI Publication No. 64-90754 discloses an ink-jet head. The ink-jet head disclosed in Jpn. Pat. Appln. KOKOKU Publication No. 2-51734 uses a piezoelectric element as an ink ejection driving element. The ink-jet head disclosed in Jpn. Pat. Appln. KOKAI Publication No. 64-90754 uses a heating resistor as an ink ejection driving element.
The ink-jet head applies a kinetic energy such as a pressure to ink in the orifice by the ink ejection driving element mounted therein and ejects the ink in the orifice from the opening at the other end. However, when bubbles are included in the ink stored in the orifice or in the vicinity of the end of the orifice in the ink storing chamber, the pressure applied to the ink by the ink ejection driving element is absorbed into the bubbles. Consequently, the ink in the orifice is not ejected from the opening at the other end. Even if bubbles are included in the ink in the ink storing chamber communicating with the orifice, a proper generation of the pressure or a proper supply of the ink from the ink storing chamber to the orifice is deteriorated in some cases.
Mixing of bubbles into ink in the orifice or in the ink storing chamber is easily caused when the ink is supplied from the outside to the ink storing chamber. While the ink-jet head is being used, the air in the external space may be mixed into the ink in the orifice or ink storing chamber via the opening at the other end of the orifice.
In the conventional ink-jet head, to eliminate bubbles mixed in ink in the orifice or in the ink storing chamber to the external space, after completion of a desired printing operation, a pressure is applied from the outside to the ink in the ink storing chamber to push out the ink in the orifice to the external space via the opening at the other end. Alternatively, a negative pressure is applied to the ink in the orifice through the opening at the other end to suck out the ink in the orifice to the external space through the opening at the other end.
In the conventional operation to eliminate mixed bubbles, it is relatively easy to eliminate bubbles mixed in a small amount of ink in the orifice. However, to eliminate bubbles mixed in a large amount of ink in the ink storing chamber, it is necessary to discharge the large amount of ink in the ink storing chamber. Even then, it is difficult to eliminate the bubbles mixed in the large amount of ink.
Jpn. Pat. Appln. KOKOKU Publication No. 6-11542 discloses a constitution which easily and efficiently discharge bubbles included in a large amount of ink in an ink storing chamber in an ink-jet head for ejecting ink in the horizontal direction to an external space. In the constitution, an orifice for ink ejection is horizontally disposed in the ink-jet head, one end of the ink ejection orifice communicates with the ink storing chamber and the other end is opened in the external space. Furthermore, in the ink-jet head, a bubble discharging path is horizontally arranged above the ink ejection orifice independently of the ink ejection orifice. One end of the bubble discharging path communicates with the ink storing chamber and the other end faces upward and is opened in the external space.
However, the constitution for eliminating mixed bubbles in the ink-jet head disclosed in Jpn. Pat. Appln. KOKOKU Publication No. 6-11542 is made on the assumption that the ink-jet head is used in a state where the ink ejection orifice is held substantially horizontally. Accordingly, when the ink-jet head is used in a state where the opening at the other end of the ink ejection orifice faces downward, the constitution does not favorably function.
In an ink-jet type printing apparatus using the ink-jet head in a state where the opening at the other end of the ink ejection orifice faces downward, the gravity can be used for ink ejection from the opening at the other end of the ink ejection orifice. Accordingly, the apparatus has such advantages that the structure of an ink ejection driving element can be easily made. The ink-jet type printing apparatus can easily and horizontally hold a recording medium while a desired image is formed on the recording medium on which the desired image to be formed. Accordingly, the surface of the recording medium is not distorted so that the printing apparatus has such advantages that a desired image can be accurately printed on the surface of the recording medium.
Accordingly, it is necessary to provide an ink-jet head which is used in a state where an opening at the other end of an ink ejection orifice faces downward and which can easily eliminate bubbles in ink in the ink ejection orifice and can also easily eliminate bubbles in an ink storing chamber.
Furthermore, it is necessary to provide an ink-jet head with a bubble extracting device for eliminating a bubble in the ink-jet head and an ink-jet type printing apparatus using the ink-jet head.
According to a plurality of embodiments of the present invention, there is provided an ink-jet head including a member having an ink storing chamber to which ink is supplied from the outside, wherein
the member includes:
at least one orifice which is mounted below the ink storing chamber and includes an end communicating with the ink storing chamber and the other end opened in an external space below the end;
an ink ejection driving element which is mounted to correspond to the orifice and ejects ink in the orifice from the opening at the other end; and
a bubble extracting path including an end communicating with an upper portion of the ink storing chamber and the other end opened in the vicinity of the opening at the other end of the orifice.
According to the embodiments of the present invention, there is provided an ink-jet head with a bubble extracting device which eliminates bubbles in the ink-jet head, the head including a member having an ink storing chamber to which ink is supplied from the outside, wherein
the member includes:
at least one orifice which is mounted below the ink storing chamber and includes an end communicating with the ink storing chamber and the other end opened in an external space below the end;
an ink ejection driving element which is mounted to correspond to the orifice and ejects ink in the orifice from the opening at the other end; and
a bubble extracting path including an end communicating with an upper portion of the ink storing chamber and the other end opened in the vicinity of the opening at the other end of the orifice, and
while ink is not ejected from the opening at the other end of the orifice by the ink ejection driving element, the bubble extracting device sucks ink from the bubble extracting path and the upper portion of the ink storing chamber through the opening at the other end of the bubble extracting path.
According to the embodiments of the present invention, there is provided an ink-jet type printing apparatus which forms a desired image on a recording medium, the apparatus comprising:
a recording medium conveyor device which conveys the recording medium;
an ink-jet head which faces the recording medium conveyed by the recording medium conveyor device and forms a desired image on the conveyed recording medium; and
a bubble extracting device which eliminates bubbles in the ink-jet head, wherein
the ink-jet head includes a member having an ink storing chamber to which ink is supplied from the outside;
the member includes at least one orifice which is mounted below the ink storing chamber and includes an end communicating with the ink storing chamber and the other end opened in an external space below the end,
an ink ejection driving element which is mounted to correspond to the orifice and ejects ink in the orifice from the opening at the other end, and
a bubble extracting path including an end communicating with an upper portion of the ink storing chamber and the other end opened in the vicinity of the opening at the other end of the orifice, and
the bubble extracting device sucks ink from the bubble extracting path and the upper portion of the ink storing chamber through the opening at the other end of the bubble extracting path while ink is not ejected from the opening at the other end of the orifice by the ink ejection driving element.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.